In the diagnosis and treatment of disease, it is often necessary or desirable to take a sample of selected tissue from a living patient, called a biopsy sample, in order to analyze the sample as an aid to diagnosis and treatment of the disease. Such a procedure can be useful in diagnosing and treating various forms of cancer, as well as other diseases in which a localized area of affected tissue can be identified. In particular, a disease associated with the formation of a tumor often indicates the desirability of taking a sample of the affected tissue.
In some cases, the tissue sample can be directly excised from the affected area, if the area is easily accessible, and highly invasive surgical procedures are not necessary. In other cases, the affected area is not readily accessible, and the biopsy sample should be taken, if possible, by means that minimize the physical trauma inflicted upon the intervening tissues that surround the affected area or target tissue. The biopsy sample procedure in such cases is typically performed by inserting a hollow biopsy needle through the intervening tissue into the target tissue to be sampled. Alternatively, a stylet with a notch in its side can be inserted, followed by a cutting cannula over the stylet. It is also possible to use the biopsy needle procedure in cases where the target tissue is easily accessible, to minimize trauma to the target tissue.
Once the biopsy needle has been inserted into the target tissue, current procedure involves the withdrawal of sample tissue through the needle by placing a suction on the needle, such as with a syringe. As mentioned above, if the notched stylet is used, it is inserted into the target tissue, then the cutting cannula is inserted over the stylet to cut the sample tissue off in the notch of the stylet. These procedures and the associated apparatus suffer from several disadvantages. First, since the biopsy needle is hollow and open at the end, pushing the needle through intervening tissues to the target area results in the accumulation of unwanted tissue in the needle, which can interfere with or complicate sample analysis.
Second, the tissue which is obtained as a sample is drawn into the needle by suction or cut by the cutting cannula, and the presently known methods require the use of two hands by the surgeon. Even using two hands, it is difficult to apply a uniform suction, quickly, through the full stroke of the syringe plunger. If suction is not applied quickly and uniformly, system leakage can interfere with obtaining a complete sample of desired tissue. Third, the size of the tissue sample is limited by the size of the opening in the leading end of the biopsy needle. Fourth, the maneuvering of the biopsy needle or stylet and operation of the associated syringe plunger or cutting cannula can be very difficult, and it typically requires the use of two hands by the surgeon. If an inadequate sample is obtained, repeated samples must be taken, increasing trauma to the patient.
Finally, the open end of a biopsy needle or the projecting edge of a cutting cannula can tear the surrounding tissue unnecessarily.
It is an object of this invention to provide an apparatus, and method of taking a biopsy sample, which requires the use of only one hand by the physician, which obtains a relatively large, uncontaminated, cleanly cut sample. It is a further object of this invention to provide a biopsy tool having a needle with a closed distal end and a lateral opening which can be selectively blocked by a cannula movably mounted on the needle, and having a means for drawing a rapid, uniform suction to pull the sample through the needle.
It is a still further object of this invention to provide a biopsy tool, having a needle with a closed distal end and a lateral opening near the distal end, having a cannula movably mounted over the needle, with its cutting edge aligned with a flat surface on the leading end of the needle, to selectively block the lateral opening, having a means for selectively locking the cannula in place on the needle, and having a means for drawing a rapid, uniform suction on the needle. It is a still further object of this invention to provide a method for obtaining a biopsy sample, by covering a needle with a cannula, inserting the needle and cannula to the affected area, moving the cannula relative to the needle to expose a lateral opening in the needle, maneuvering sample tissue into the lateral opening, cutting sample tissue from the affected area, and steadily but quickly drawing the sample tissue through the needle.
Finally, it is an additional object of this invention to provide a biopsy tool which is relatively cost effective to make and relatively easy to use.